1. Field of the Invention
The invention relates to a method of selecting a channel for executing a communication from a plurality of communication channels.
2. Related Background Art
In a conventional wireless telephone system, when an information signal is transmitted and received between a fixed apparatus and a moving apparatus, the fixed apparatus selects a free channel from a plurality of speech channels and transmits data regarding the selected free channel through a control channel and communicates with the moving apparatus through the speech channel.
In such a wireless telephone system, the speech channel to connect the fixed apparatus and the moving apparatus is allocated on the basis of the result of the discrimination regarding whether the speech channel is free or not at the allocation time point. When a communication speech is performed by using a free speech channel designated by the control channel, in the case where the connection of the speech channel fails, the connecting operation is interrupted and another free speech channel is newly searched and the connecting operation is again executed from the connection of the control channel on the basis of the free speech channel.
Hitherto, there is also a case where when the connection becomes impossible after a few retrials were performed in order to connect the speech channel for the connection fault of the speech channel, another free speech channel is allocated and a similar trial of the connection is performed.
Hitherto, to avoid a cross modulation of the wireless telephone systems, the allocation of the speech channels of frequencies of harmonics which are odd-number times as high as the basic frequency is inhibited.